Dynamic Sampling Barrels

This is now a very popular technique for shallow geotechnical and geo-environmental work. Dynamic sampling is an effective way of sampling soil, made ground fill and over-burden, relatively quickly by driving in sequential sample barrels, either using a percussive hammer, drop hammer or static pushing force, driven 1.0m or 1.5m sample runs.

You can recover a reasonably accurate soil profile, retained in the plastic liners used in the dynamic sample barrels. There is a range of different diameter dynamic sampling barrels giving a sample core size of anywhere from 113mm down to 35mm to a recognised standard of Class 3 – 4 quality in accordance with BS 5930:2015 Chapter 25.8.2.

The sample barrel consists of an outer barrel, with a cutting shoe, a threaded back end with a non-return air valve to retain the sample and it allows air to escape as the sample is driven into the plastic liner place in the sample barrel, reducing sample compaction and disturbance. The plastic sample liner has a metal retaining ring to keep it centralised in the cutting shoe, which can be swapped for a plastic catcher for retaining wet sands and fine gravels or steel fingered ring for retaining soft fine-grained soils.

A great feature is that casing can be driven in simultaneously or more commonly termed “duplexed” with the dynamic sample run thereby keeping the borehole open and maintaining sample quality in loose and weak ground conditions or where water is present. Casing is especially useful for holes where an installation is required.